1. Field of the Invention
The present invention relates to a voice synthesis device, a voice synthesis method, and a recording medium having a voice synthesis program stored thereon.
2. Description of the Related Art
Examples of a voice synthesis technology of this kind include a vocal synthesis technology for electronically synthesizing a singing voice based on information indicating a string of notes composing a melody of a piece of music (in other words, information indicating a change in rhythm of a melody; hereinafter referred to as “music information”) and information indicating lyrics to be vocalized in synchronization with the respective notes (information indicating a phoneme string composing lyrics; hereinafter referred to as “lyrics information”) (see, for example, WO2007/010680, Japanese Patent Application Laid-open No. 2005-181840, and Japanese Patent Application Laid-open No. 2002-268664). In recent years, application software for causing a general computer such as a personal computer to perform such vocal synthesis is widely distributed. Examples of the application software of this kind include a set of a vocal synthesis program and a database for vocal synthesis storing pieces of waveform data on various phonemes which are extracted from voices of a voice actor or a singer.
The vocal synthesis program is a program for causing the computer to execute processing for reading the pieces of waveform data on the phonemes designated by the lyrics information from the database for vocal synthesis, subjecting each piece of waveform data to pitch conversion so as to achieve a pitch designated by the music information, and combining the pieces of waveform data in pronunciation order, to generate the waveform data indicating a sound waveform of the singing voice. Further, in some vocal synthesis programs, not only the phoneme string which composes lyrics and pitches exhibited when the lyrics are pronounced, but also various parameters which indicate a vocalization manner of a voice such as velocities and volumes exhibited when the lyrics are pronounced, can be designated finely in order to obtain a natural singing voice that is close to a human singing voice.